PL
A phenomenological standard two-sublattice mean-field model was discussed. The Mn-Mn interaction is assumed to be linearly dependent on the unit-cell dimensions, giving rise to magnetostrictive phenomena. The (P,T) magnetic phase diagram for R1-xR’xMn2(Ge, Si)2 series of compounds was discussed and the magnetic phase diagram parameters derived from the experimental data were used for the theoretical calculation.